Gyroscopic azimuth stabilizer and hydraulic drive for a gun



Nov. 15, 1955 L. B. M. BUCHANAN 2,723,596

GYROSCOPIC AZIMUTH STABILIZER AND HYDRAULIC DRIVE FOR A GUN 4 Sheets-Sheet 1 Filed April 23, 1947 Jwucwfo'n LE5 LIE E-M.E1u EHANAN jyiyiiz ww y/a Nov. 15, 1955 B. M. BUCHANAN 2,723,596

GYROSCOPIC AZIMUTH STABILIZER AND HYDRAULIC DRIVE FOR A GUN 4 Sheets-Sheet 2 Filed April 23, 194'? 4 Sheets-Sheet 3 Filed April 23, 1947 LE5| |EE M.B LIEHANAN,

United States Patent GYROSCOPIC AZIMUTH STABELIZER AN D HYDRAULIC DRIVE FGR A GUN Leslie B. M. Buchanan, Wiibraham, Mass. Application April 23, 1947, Serial No. 743,286 Claims. (Cl. 39-41) This invention relates to azimuth stabilizing and traversing mechanisms for guns. The invention will be described in connection with a cannon mounted for elevation on and traversable in azimuth with the turret of a tank. It will be appreciated, however, that the invention is not limited to the particular installation selected for disclosing the invention. With only minor changes, if any, the invention is readily adapted for use in connection with any gun flexibly mounted upon an unstable platform whether it be carried by a land vehicle, aircraft or a ship.

The main guns of a tank are commonly mounted for movement in azimuth as a unit with the tank turret and, of course, elevatable about normally horizontal axes with respect to the turret. Power drives are commonly employed to effect combined rotation of the turret and guns relatively to the tank chassis. These drives are under control of the gunner or alternatively, the tank commander, so that the direction and rate of traversing of the gun may be varied as conditions require.

When the tank is firing while at rest, simple manual control of the power drive or even direct manual traversing of the gun, are sufficient. However, when the tank is firing while motion, the yaw produced by uneven terrain, and necessary frequent changes in course while maneuvering, make it virtually impossible for the gunner to keep his guns accurately trained upon a remote target. Furthermore, in case there is relative movement between the tank and target, it is usually necessary to continuously alter the azimuth of the gun for a successful engagement.

It is therefore an object of the invention to provide a power drive for controlling a gun in azimuth, wherein shift from manual to automatic operation, and vice versa, may be effected substantially instantaneously.

Another object is to provide a power-drive for traversing a gun mounted upon a movable or unstable platform wherein the drive may be automatically controlled to maintain the gun unaffected by yawing or turning of the platform, While, at the same time, the drive may be manually controlled to effect the relatively slow azimuthal movement necessary to continuously engage a target while the platform is in motion.

A further object is to provide a gyroscopic control for the traversing power drive of a gun mounted upon an unstable platform wherein the precession of the gyroscope induced by yawing of the vehicle acts to control the power drive to render the gun unaffected by said yawing, while the gyroscope may be manually caused to precess to effect a desired steady rate of traverse of the gun.

A still further object is to provide a system for conversion from automatic to manual control, and vice versa, that is so coordinated with the power drive as to instantaneously condition the latter for either type of control as selected by the gunner.

Another object is to provide a hydraulic azimuth drive for tank turrets and the gun or guns carried thereby, that is capable of selective manual or automatic gyroscopic control and that, in both cases, aifords a means for accurately traversing and stabilizing the gun in azimuth,

while at the same time being rapid in action and response to the controls.

Another object is to provide a gyroscopic azimuth stabilizer in combination with a power drive wherein the rate of stabilizing action will be directly proportional to and automatically responsive to the angle of precession of a gyroscope carried upon the stabilized object.

A further object is to provide an azimuthal control sys- A tem for a gun mounted upon a mobile base wherein a single handle is operable either to directly control the rate and direction of gun traverse or to modify the automatic control to effect traverse in a desired direction in addition to the stabilizing action rendered necessary by yaw and change of course of the mobile base.

Other objects and advantages of the invention will become apparent as the description progresses.

In the drawing:

Figure 1 is a sectional elevation diametrically through a tank and its turret showing schematically the power drive for rotating the turret.

Figure 2 i is a schematic view showing the hydraulic system for controlling the rate and direction of rotation of the tank turret, together with the means for effecting shift from automatic to manual control and vice versa, by

' means of a single control element.

Figure 2a is a diagrammatic view showing the followup connections by which the precession of the control gyroscope effects a proportional displacement of the pump rotor and angular speed in azimuth of the gun and turret.

Figure 3 is an enlarged detail view, partly in section, showing the knob and connections for simultaneously moving the manual control cam out of operating position and throwing a switch to connect the gyroscopically-controlled rheostat for automatic operation.

Figure 4 is a sectional detail view taken upon the line 4-4, Figure 3 showing a feature of the switchactuating disc.

Figure 5 is an enlarged detail view of the control handle used for both direct and gyroscopic azimuth control of the turret and gun.

Figure 6 is an elevation of the follow-up contacts used to control the hydraulic motor connected to operate the slide block of the pump whereby the block is displaced, and the pump, and motor driven thereby, are operated at a speed proportional to the angle of gyroscopic precession.

Figure 7 is an elevational view of the same parts as are shown upon Figure 6, and taken upon a plane indicated by the line 7-7, Figure 6.

Figure 8 is an elevation, partly in section, of the gyroscope, silverstal operated thereby, and spring means for inducing precession of the gyroscope.

Referring in detail to the drawings, 1 identifies a portion of a tank body, having a large internal ring gear 2 fixed to the floor thereof. A turret 3 is rotatably mounted on the tank by means of supports 4 carried by a ring 5. The ring 5 is rotatably mounted on gear 2 by antifriction means such as balls 6. A shaft 7 is journaled on ring 5 by bearings not shown, and at its lower end carries a pinion 8 in mesh with gear 2 and at its upper end a gear 9 meshing with a pinion 10 fixed to the shaft of a hydraulic motor 11. By this construction rotation of the motor efiects rotation of the turret 3 and its gun 12, which is pivoted on the turret for elevation about trunnions 13.

Motor 11 may be any suitable type of hydraulic machine and, except for the slide block and control means therefor, may be of the same general construction as its supply pump, indicated generally at Figure 2 by the numeral 14. This pump is of the well-known rolling and rotating piston, variable displacement type comprising a casing 15 having a central chamber 16 within which a slide block 17 is guided for translation by parallel spaced guide surfaces 17a and 17b on the casing and block and between which surfaces fit anti-friction means such as the roller slides 18 and 19. A drive shaft, not shown, connected to a prime mover, such as an electric motor, is journaled in casing on an axis fixed relatively thereto and carries a rotor 20 having radial, axially-inclined cylinders 21 bored therein, within which fit the pistons 22. The slide block 17 is cored to receive the roller bearing 23. The inner race of this bearing surrounds and contacts the ends of the pistons when the pump is operating. The flat ported valve 24 is fixed to the casing and has suction and discharge ports with which ports leading from the inner ends of cylinders 21 communicate in proper sequence, as the rotor turns. Conduits 25 and 26 lead from valve 24 and, depending upon the position of the slide block, either may be a discharge conduit while at the same time, the other is a suction or intake conduit. For example, in the position of the parts and direction of rotor rotation shown upon Figure 2, discharge will be through conduit 26, while 25 will then constitute the return or suction line.

As shown, the aforesaid conduits lead to ports 27 and 28, respectively, of motor 11. Also each has a branch 30 and 31, leading to a relief valve 29 which, in turn, is connected by a conduit 32 to oil reservoir or sump 33. A drain pipe 34 connects motor 11 with reservoir 33.

Translation of the pump slide block 17 along the ways in casing 15 acts to vary the direction and rate of flow of fluid to and from motor 11. The position of the slide blocx is controlled by a cam and piston assembly 35 translatable in a part of the pump casing, in conjunction with a pressure piston 36, reciprocable in a cylinder 37 secured to the casing in alignment with the direction of movement of the slide block 17. The pump has a natural tendency to center itself. That is, if unrestrained, slide block 17 will move to a neutral position, such that bearing 23 is coaxial of rotor 20, in which position the pistons do not reciprocate on rotation of the rotor 20, and there is no delivery of the pump. Therefore, when the nose 38 of the slide block is on the positive side of cam 35, such that the block is moved to the left of the aforesaid neutral position, the tendency of the block to return to such position is sufficient to hold nose 38 against the cam. Figure 2 shows the slide block at its substantally maximum positive position so that the pump, when rotated, has maximum delivery through conduit 26 to drive motor 11 in one direction and traverse turret 3 at maximum rate in a corresponding direction.

- Because of the aforesaid centralizing tendency, a force must be applied to slide block 17 to hold nose 38 against cam 35 over the negative half of the cam, that is, when the block is to be displaced to the right of neutral position, Figure 2, so that discharge takes place through conduit 25, to drive motor 11 and turret 3 in a reverse direction. This force is supplied by piston 36 and its rod 39 attached at one end to block 17 by application of pressure to piston 36, through conduit 65 or 66, in a manner that will be subsequently described.

The cam assembly 35 includes a relatively large piston 41 mounted on one end of cam 35, and a relatively smaller piston 42 mounted upon the other end of said cam. The pistons are accommodated in respective aligned cylinders 43' and 44 formed in the pump casing block. Piston 42 is directly and continuously subjected to the pressure developed by a simple auxiliary gear pump 45, shown as mounted in the casing block of pump 14 and having its discharge or pressure side connected with cylinder 44 over a passage 46. Pump 45 is supplied with fluid from reservoir 33 over an intake conduit 47. Excess fluid discharged from this pump is returned to sump 33 over line 57.

It will be understood from the foregoing that the dircction and rate of delivery of pump 14, depends upon the position of cam 35 relatively to nose 38. This position is controlled by a pilot valve 48 slidable within a cylinder block 49. The valve 48 is of the well-known balanced type with a central piston 50 movable to either side of radial openings in block 49, which openings are in communication with a passageway 51 leading to the outer end of cylinder 43. A second series of radial apertures in block 49, communicate with a passageway 52 leading from cylinder 44 and a third series of apertures communicate with a drain passageway 53 connecting the interior of the pump externally of block 17, with a chamber 54. A drain conduit, 55 connects chamber 54 with reservoir 33.

The piston valve 48 is urged to the right, as seen in Figure 2, by a spring 56 seated in a recess in casing 15. This spring acts to maintain operating contact between valve 43 and a control equalizer lever 58 positioned within chamber 54. The other end of lever 58 bears against one end of a follow-up pin 59 which has a smooth fit in a bore in casing 15. The other end of this pin projects into the chamber between pistons 41 and 42, and there bears upon the bottom of a cam groove 60. At a point intermediate its ends, lever 58 bears against a pin 61 fixed to a pivoted handle 62. The pin is positioned eccentrically of the pivot. As the lever is continuously held in contact with pin 61 by the action of spring 56 and valve 48, rotation of the handle acts to pivot lever 58 about its point of contact with pin 59, as a fulcrum and thus moves valve 48. Depending upon the direction of rotation of the handle, movement of valve 48 acts ('1) to connect the source of pressure from pump 45 and passage 52, to passage 51 and large cylinder 43 or (2) to connect such cylinder over passage 52 to exhaust passage In the case of (l), the piston 41, being of larger area than 42, overpowers the thrust of pressure fluid acting continuously thereon and moves cam 35 downwardly, as seen in Figure 2. Pressure acting upon piston 36 is thus free to translate the slide block 17 to the right to keep nose 38 in engagement with the cam and cause the pump todischarge through conduit 25 at a rate corresponding to the displacement of the block to rotate motor 11 and train gun 12 in one direction. In the case of (2), the cylinder 43 above piston 41, is connected to exhaust so that the fluid pressure acting upon piston 42, is free to move the cam upwardly, translate slide block 17 to the left as seen in Figure 2, and reverse the direction of discharge of the pump and cause motor 11 to train gun 12 in the opposite direction.

Without cam groove and pin 59, rotation of handle 62 in either direction from central or neutral position, would simply cause cam 35 to move to one or the other of its extreme positions and cause the pump to deliver at maximum rate in a corresponding direction. How ever, the bottom of cam groove 60 is so shaped as to translate pin 59 and lever 58, to restore valve 48 to neutral or centralized position whenever cam 35 has been shifted an amount corresponding to the rotation of handle 62. Thus cam 35 is brought to rest at a position dependingupon and proportional to, the angle of rotation of handle 62, and the pump discharges, and the gun is trained, at a rate proportional to such angle.

The construction described in the foregoing paragraphs is old and well known and is standard equipment in certain of the Armys tank models. When it is desired to provide gyroscopic control of pump 14 by varying the pressure of the fluid applied to opposite sides ofpiston 36, it is necessary that cam and piston assembly 35 be moved to and retained in fully downwardly translated position as viewed in Figure 2. This moveemnt separates nose 38 from the cam and permits the slide block to be operated freely under the sole control of piston 36'.

In carrying out my invention, I use a hydraulic system which may be similar to the one disclosed in the patent to Taylor 2,381,162, August 7, 1945, wherein differential portion of cylinder 44, with energization of two coils under the operation of a control device, acts to control the direction and rate of flow of fluid in a hydraulic circuit. Since the system is well known, I have shown only the control coils thereof, at 63 and 64, Figure 2a, together with the two supply conduits 65 and 66 entering cylinder 37. It will be understood .that, similarly to the construction shown in the aforesaid patent to Taylor, when coil 63 is energized to predominate over coil 64, hydraulic pressure is applied to the right side of cylinder 37, through conduit 66, and exhausted through conduit 65, to thereby move slide block 17 to the left, as seen in Figure 2a. On the other hand, when the energization of coil 64 predominates over 63, fluid pressure is applied to the cylinder through conduit 65 and exhausted from conduit 66, to move slide block 17 to the right.

Under manual control by operation of handle 62, and because of the aforesaid tendency of the slide block 17 to move to neutral or no-discharge position, it is necessary to continuously apply pressure through conduit 65 to urge piston 36 to the right, Figure 2a, and thereby hold nose 38 against cam 35, when, and only when the negative portion of cam 38 is being used. That is, pressure must be applied through conduit 65 for all positions of the slide block 17 to the right of its central position, corresponding to discharge of pump 14 through conduit 25. On the other hand, during manual control, no pressure on piston 36 is required when the positive portion of cam 35 is being utilized since, in that situation, the natural tendency of the slide block to move to central position effectively holds nose 38 in engagement with cam 35 and any application of force through piston 36 would be superfluous and cause excessive wear.

To care for this situation, I have provided, as schematically shown upon Figures 2 and 2a, a switch 67 comprising a live contact 68, a dead contact 69, and a switch lever 70. The lever 70 is connected by a link 71 to one end of a rod 72. This rod projects through a gland in the wall of casing 15 where its other end is attached to piston 42. The arm and contact 68 are so arranged that the two are in engagement at all times during movement of the negative half of cam 35 over nose 38. However, as soon as cam 35 begins to move slide block 17 to the left, Figures 2 and 2a, of its central position, lever 70 moves 01f contact 68 and opens the circuit of coil 64. De-energization of coil 64 releases all pressure in conduit 65 and upon piston 36. While I have shown switch 67 as mounted exteriorly of casing 15, it is clear that it might alternatively be mounted within an enlarged end terminals only, extending through the casing wall.

It has been previously explained that, for automatic control, cam 35 should be moved to full negative position in which the cam and piston assembly is in its lowermost position as viewed in Figure 2. This movement is accomplished by shifting pilot valve 48 to the left as viewed on Figure 2, to thereby apply the full hydraulic pressure of pump 45 to piston 41. To accomplish this function, I have provided a pin and slot connection between lever 58 and valve 48, shown as a pin 73 on lever 58 engaging a slot 74 in valve 48, or an extension thereof. This connection, while in no way afiecting the operation of valve 48 from handle 62 during manual azimuth control, enables the valve 48 to be shifted to the left, Figure 2, when automatic or gyroscopic control is to be used.

For manual shifting of valve 48, there is provided a rod 75 thereon, extending through the casing wall and terminating in a knob 76. On its end within the chamber 54, rod 75 has a disc 77 positioned to bear against the end of valve 48 so that, as the knob is pushed inwardly, valve 48 is moved to connect conduits 52 and 51. Referring to Figure 3, rod 75 carries a catch disc 78 exteriorly of the casing. This catch, as shown at Figure 4, has a notch 79 and a depression 80 in its periphery for cooperation with a pin 81, Figure 3, carried by a bracket 82 fixed to the casing wall. A switch 83 is also mounted upon the casing wall below rod 75 and has an arm 84 with a forked end embracing the rim of catch 78 to thereby close and open the circuits as knob 76 is moved inwardly and outwardly. The function and operation of this switch will be subsequently described in detail. In operating the knob, it is first rotated until notch 79 is aligned with pin 81, then pushed inwardly until the catch clears the pin. The knob is then rotated until depression 80 is aligned with the pin. On release of the knob, spring 56 acts to seat the pin in the depression and hold it in such position until released by an operation the reverse of that just described. Simultaneously, switch 83 is actuated between a first and a second operating position. In short, when knob 76 is in its outermost position, the system is conditioned for manual control and the gun is trained in a direction and at a rate corresponding to the direction and angle of rotation of handle 62. When the knob is pushed inwardly, the system is conditioned for automatic operation under the control of a gyroscope, to be described. However, in the latter situation, the gun may still be trained by precessing torques applied to the gyroscope from handle 62, as will also be explained.

The details of the handle 62 and its connection with the gyroscope, are shown at Figure 5, wherein are identified the eccentric pin 61 adapted to pivot control equalizer lever 58, in the manner previously described. The pin 61 is formed upon the inner end of handle shaft 85. This shaft is journaled in an aperture extending through that portion of pump casing wall forming chamber 54. Cover plate 86 on which rod 75 and switch are mounted, is also identified in Figure 5. Shaft is enlarged at its outer end and has handle 62 fixed thereto by socket head screws 87.

A pin 88 has a drive fit in handle 62 olfset from shaft 85 and extends through a hole in a cable pulley 89 so that the handle and pulley rotate as a unit. The pin extends further between the offset ends 91 and 92 of a return coil spring 90. A disc 93 is fixed to casing 15 in any suitable manner, and has a pin 94 also projecting between the aforesaid ends of spring 90. Thus the spring acts to urge pins 88 and 94 into alignment radially of shaft 85 and to return handle 62 to a predetermined position whenever it has been deflected in either direction therefrom. This position is, of course, that corresponding to central position of valve 48 and central or neutral position of slide block 17, wherein the turret and gun are at rest.

The gyroscope and its mounting are shown at Figure 8. Although shown as mounted upon a portion of turret 3, it may if desired, be mounted on a portion of the tank apart from the turret. A platform 95 is mounted upon any suitable portion of the turret, for pivotal movement about a normally vertical axis, by means of a shaft 96. This shaft supports the platform and is journaled in suitable bearings, not shown, carried by the turret and a bracket 97. A cable pulley 98 which may be identical with pulley 89, is journaled on shaft 96. Pins 99 and 100 are secured to this pulley and a disk 101, respectively. Disc 101 is secured to the shaft 96 by a set screw and a coil spring 102 surrounds the shaft 96 and urges pins 99 and 100 to aligned position in the manner just described for spring 90 and pins 88 and 94, Figure 5.

The gyroscope designated generally by numeral 103 is preferably mounted adjacent the pump 14 and a cable 104 connects pulleys 89 and 98 so that pivotal movement of handle 62 acts through spring 102 to apply a precessing torque to gyro 103, the torque being proportional to the angle of pivotal movement of the handle 62.

The gyroscope consists of a rotor, not shown, journaled in a casing 106 for spinning about a normally horizontal axis 107 shown as normal to the plane of the paper upon Figure 8. The rotor may consist of the armature and flywheel connected thereto having the desired combined moment of inertia and supplied with current by leads not shown. The casing is journaled for precession about, a second normally horizontal axis, at right angles to. its spin axis, by trunnions 108 and 109 which may be attached to the casing 106 and journaled in uprights of a frame 110 fixed to platform 95. The axis defined by trunnions S and 109 is normal to and concurrent with, the spin axis. Thus, when spinning and a torque is applied thereto about the axis of shaft 96, by spring 102, the gyroscope precesses about the axis of trunnions 108i and 109 in a direction dependent upon the direction of spin and the direction of the applied torque. Too, in accordance with well-known laws of the gyroscope, the angle of precession will be proportional to the value; of the torque. The gyroscope is of a type conventionally knownas a two-degree-of-freedom constrained rate-responsive gyroscope.

A bracket 112 is fixed to the top of casing 106. This bracket has an apertured, upstanding arm 113 to which is attached a spacer 114 of insulating material such as Micarta. As more clearly shown upon Figure 2a, this spacer projects between the innermost ones of two setsof spaced contact leaves 115 and 116. These two sets of leaves, together with their resistors constitute what is generally known as a Silverstat. Since these Silverstats are well known in the art, being shown in the aforesaid patent to Taylor, as well as the patent to Hanna, 2,404,172, July 16, 1946, it is deemed unnecessary to describe them in detail. Suffice it to say that the leaves possess an inherent resilience and are anchored and insulated from. each other at their inner ends. Each leaf is connected to a respective resistance, all of which are connected in series. Hence as the outer or free ends of: a. series of, leaves are moved into or out of contact, the resistances are shorted out of, or cut into, the circuit, respectively, to vary the total effective resistance of the circuit including that resistance. From Figure 2a, it will be noted that the spacer 114 is of a width sufiicient, when in normal or unprecessed position, to maintain in electrical contact an equal number of the inner leaves of each set. Hence, movement of the spacer in one direction acts to successively close additional leaves of one set. and to cause separation of a corresponding number of leaves of the other set to thus differentially vary the two resistances.

From Figure 8 it will be noted that casing 106 carries a counterweight 117 which may be in the form of a nut threaded upon, a stem 118' projecting downwardly from casing 106. By adjusting the nut, the weight of bracket 112 and parts carried thereby may be balanced. When in such balanced condition, the center of gravity of casing 106 and all parts carried thereby, will be at the common intersection. of axis 107, the axis of trunnions 108, 109, and the axis of shaft 96. The Silverstat and its resistors 118 and 119, are carried by a standard 120 supported on platformv 95. Only one resistor 118, appears in Figure 8. Each blade is connected with its resistance by a respective conductor. These conductors are combined in a multi-strand cable 121, as indicated at Figure 8. Since the angles of precession of gyroscope 103 and turning of platform 95 relatively to its support, are always small, ordinary pig-tail lead-in connections to the gyroscope and resistors are sutficient, no slip rings or brushes being required. For that reason, such connections are omitted upon Figure 8.

The. moment of inertia of the gyroscope rotor and its angular velocity of spin are constant. Furthermore, precession will be yieldingly opposed by the Silverstat leaves-with a force substantially proportionalto the'angle of. precession. Hence, in accordance with a well-known law, the angle of precession will be proportional to the torque applied by spring 102, which, in turn, will be closely proportional to the deflection or rotation angle of, handle 62 and in a direction corresponding to the di-. rection. of rotation of the handle. Likewise, thedifferential change in energization of resistors 118 and: 119 willbean a. determinable relationto the-angle of precession. It remains, then, to utilize this differential change to proportionally translate piston 36 and slide block 17, to assure that, when under gyroscopic control, the gun and turret will be stabilized in azimuth despite yawing and turning of the tank while, at the same time, changes in azimuth of the gun may be eifected manually by handle 62 acting through the intermediary of the gyroscope, as previously described. If desired, of course, additional constraint may be provided for gyroscope 103, in addition to that afforded by the silvestat. Such a constraint for example, might be a coil spring arrangement similar to that shown at 99-4102, and acting about the axis of trunnions 108-109 to yieldingly urge the gyroscope into the position shown at Figure 8.

The follow-up feature which enables effectuation of this function and which forms an important part of my invention, is shown in detail at Figures 6 and 7. On Figure 7 there are identified a portion. of pump casing 15, slide block 17, piston rod 39, cylinder 37, and piston 36, all reviously described. Rod 39 continues through a gland 3.2-2 carried by a cylinder head 123 closing the. outer end of the cylinder. A base 124 is fixed to the under side of cylinder 37 and at its outer end carries a plate 125. At its left end, as seen in Figure 6, plate 125 has a bearing bracket 126 fixed thereto. A rod 127 is fixed in this bracket with its axis parallel to plate 125. A sleeve 128 is fixed on rod 127 and has radial arms 129 and 130 formed integrally therewith. Solenoids 131 and 132 are attached by clamps 133 and 134, to the arms, respectively, in positions to extend concentrically of the axis of shaft 127. One terminal of each solenoid is connected to a common terminal on a block 135. Each of the remaining two terminals of the solenoids is connected to respective terminal on block 135.

A trolley arm 136,. is journaled on rod 127. The arm has a downward projection 136 which passes through a slot in an arcuate tube 137 fixed to plate 125. The tube has closed ends and two coil springs 138 and 139 are positioned in the tube, on opposite sides of projection 136'.

.he springs thus act to urge the trolley arm to a centralized upright position, while permitting limited rotation thereof. At its upper end, arm 136 carries an arcuate armature 140 concentric of the axis of rod 127. This armature passes through solenoids 131 and 132 and is adapted who moved in one direction or the other, on differential energization of the solenoids. Arm 136 has a link 141 pivoted tov its upper end. The other end of this link has a second link 142 pivoted thereto; The other end of link 142 has a trolley 143 journaled thereon.

A light coil spring 144 is connected between a pin on arm 136 and link 142 and thus acts to urge the trolley into engagement with an arcuate contact element 145. In order to avoid confusion between the parts, this. element is shown upon Figure 2a as displaced 180 from the preferred position of Figures 6 and 7. However, it will be best noted from Figure 2a, that the contact comprises two arcuate contacts 145a and 145b, separated by a nonconducting portion145c.

The element 145 is concentric of the axis of rod 127 and is-carried by, but electrically insulated from, an arm 146 fixed to a rod 147. This rod is journaled inthe bearing of a bracket 148 fixed to. base 125. Rods 127 and 1 47 are coaxial. Also fixed to rod 147 is a pinion 149. A rack 150 has backing rollers 151 journaled on av support 152 fixed to plate 125. This-rack is attached to the projecting end of rod slide block 17 and-piston 36. Furthermore, translation of the rack acts to pivot element 145 about the common axis of rods 127- and 147.

From Figure 2a, it will benoted that the outer. ends of resistors 118 and 119 are connected by leads'153' and 1.54 to the corresponding ends of' coils 131 and 132', respectively. The common terminal of' these coils is grounded at 155. The adjacent inner ends of the resistors areconnected bya lead 156 to one terminal'of a calibrating or stifiness rheostat 157 whose adjustable element 39 and thus moves as a unit withv is connected by lead 158 to one terminal 159 of switch 83. The center terminal 160 of this switch is connected to one terminal of a source of D. C. potential. The third terminal 161 is connected to contact 68. From the switch arm 70 of switch 67, a lead 162 extends to one terminal of coil 64. This terminal is also connected to contact 145b. Contact 145a is connected by lead 163 to a terminal of coil 63. The two coils have a common terminal grounded at 164. A lead 165 extends from terminal 159 to trolley arm 136.

It has been previously explained that coils 63 and 64 control the application of a source of hydraulic pressure, to two outlets. These outlets are identified at 65 and 66, Figures 2a and 7. In the latter figure, it will be noted that they are connected to ports in cylinder 37 upon opposite sides of piston 36. Thus, when the system is in automatic control and coil 64 predominates, pressure in conduit 65 acts to move piston 36, slide block 17 and rack 150, to the right, as seen in Figure 2a. When'coil 63 predominates, pressure is applied to conduit 66 to shift the slide block in the opposite direction.

In operation, suppose that it is first desired to aim the gun under direct manual control until the gun is properly trained upon a target, and to then shift to automatic azimuth control. With all pumps operating and master switches closed, knob 76 is moved outwardly if not already in such position. This acts, first to release valve 48 and to permit spring 56 to move the end of slot 74 into engagement with pin 73. Secondly, such movement of knob 76 actuates switch 83 to connect the source of potential to contact 68 of switch 67. Since contact 159 is now dead, movement of trolley 143 over the contact element 145, has no eflect on coils 63 and 64. Thus the gyroscope may spin and precess in a normal manner during manual control, but has no efiect on the pump 14. The handle 62 may now be turned or twisted in one direction or the other, depending upon the desired direction of rotation or' training of the gun and turret. When the desired movement is in a direction corresponding to the negative half of cam 35, switch arm 70 is in engagement with contact 68. Coil 64 is thus energized by way of the D. C. source, terminals 160, 161 and 68, arm '70, lead 162, and coil 64 to ground at 164. Energization of coil 64 causes the application of hydraulic pressure to conduit 65 and thus acts to hold nose 38 of slide block 17 firmly against the edge of cam 35. However, when the desired direction of gun training corresponds to the positive half of cam 35, no hydraulic pressure on piston 36 is required since, as previously explained, the pump has an inherent tendency to move its slide block to central or no discharge position and thus maintains its nose 38 against the cam. Thus the cam and piston assembly are so related with switch 67 that lever 70 moves out of engagement with contact 68. just as the slide block has moved slightly to the left of central position, as viewed upon Figures 2 and 2a. This acts to de-energize coil 64 and to relieve pressure on piston 36 whereby unnecessary pressure and wear on the pump parts are avoided.

As soon as the gun has been manually directed onto the target, and automatic control is desired, knob 76 is pushed inwardly to move disc 78 past pin 81. The disc is then turned and released to permit spring 56 to move the depression 80 in the disc into contact with the pin. Inward movement of'knob 76 positions valve 48 to connect passageways 52 and 51 and thus subject piston 41 to full pressure from pump 45. As a result, cam 35 is moved downwardly its maximum distance and slide block 17 is freed from any control thereby. At the same time, switch 83 is operated to connect terminal 159 to the source of current and to disconnect terminal 161 therefrom. The gun is now under automatic azimuth control.

Assuming that the parts are in the position shown at Figure 2a, that is, before any precession of gyroscope 103 has taken place, the effective resistance of each resistor 118 and 119 is the same, and current passes from the source to contacts 160, 159, lead 158, rheostat 157 and lead 156 where it divides equally, one portion going through resistor 118, line 153, coil 131' and lead 155 to ground. The other portion passes through resistor 119, line 154, coil 132 and lead 155 to ground. Solenoids 131 and 132 are thus equally energized and trolley 143 remains on insulation 145c so that both coils 63 and 64 are de-energized.

Should the tank now yaw or change its course, a torque is applied thereby to gyroscope 103, causing it to precess about the axis of trunnions 108 and 109 in an amount and in a direction dependent upon the rate and direction of yaw. The resulting movement of spacer 114 acts to close additional silverstat leaves of one set, and to open a corresponding number of the other set. Suppose, for example, that the precession is such that spacer 114 moves to the left as viewed at Figure 2a. Additional leaves 115 are thereby closed while a number of leaves 116, previously in contact, are separated. The efiective resistance of resistor 118 is thus lowered and that of 119 is increased. As a result the energization of solenoid 131 is augmented and that of 132 is decreased. The armature 140 is thus moved toshift trolley 143 into contact with segment 145b. This movement is opposed by spring 139 so that the movement is tional to spring distortion.

As soon as the trolley moves onto segment b, coil 64 is energized by way of switch 83, lead 165, arm 136, trolley 143, segment 145b, and coil 64, to ground at 164. The energization of coil 64 causes the application of fluid pressure to conduit 65 and thus to piston 36. The piston and slide block are thus moved to the right, Figures 2 and 2a, thus causing the pump 14 to discharge in the direction necessary to operate motor 11 and gun 12 in a direction opposite to the direction of yaw. At the same time rack drives pinion 149 to cause element 145 to follow-up trolley 143 until insulation 145a is again under the trolley and the circuit to coil 64 is broken. However, any tendency of the pump to return to neutral, as long as the trolley is displaced, will again close the circuit to coil 64. Pressure in conduit 65 is thus maintained as long as the trolley is deflected.

Since the trolley and slide block are displaced an amount proportional to the rate of yaw and the gun is turned during the time the yaw takes place, and at a rate equal and opposite thereto, it is clear that the gyroscope when in sole control, acts to effectively stabilize the gun in azimuth for both directions of yaw or change of tank heading. When the tank is in motion and engaging a fixed or moving target, it is usually necessary to give the gun a slow movement in azimuth to keep it trained upon the target. This function may be effected by turning of handle 62 to thereby apply a precessing torque to gyro 103 through cable 104 and spring 102. Since the torque applied to the gyroscope will be the algebraic sum of that due to yaw and that applied by handle 62, the two functions may take place simultaneously so that the gun may be properly stabilized in azimuth while at the-same time given a target-following movement. While I have shown the segments 145a and 1451: as being controlled by piston 36 and trolley 143 as controlled by solenoids 131 and 132, it is contemplated that the arrangement shown may be reversed, with the trolley controlled by piston 36and segments 145a and 145b controlled by the solenoids.

Thus I have provided an azimuthal gun training end stabilizing system that may be instantly converted from full manual control to automatic gyroscopic control with supplemental manual control. Because of the follow-up feature of Figures 6 and 7, the rate of gun movement in automatic control is substantially directly proportional to the rate of yaw over the entire available range of rates while in manual control, the rate varies directly with displacement of the handle.

While I have shown a preferred form of the invention as now known to me, various modifications and substitutions will be obvious or readily occur to those skilled substantially propor- 1, 11 in the .art after a study-of thezpresent disclosure. Hence :the foregoing tdisclosureshould be taken in=an illustrative, rather than a limiting sense; and 'I desire .to reserve all such changes as fall within the scope of the subjoined claims.

Having now fully disclosed .the invention, what I claim and desire to secure by Letters Patent is:

1. In .a system adapted .to be .used for the azimuth stabilization and control of a gun mounted upon amobile base for training about a normally vertical axis, a hydraulic motor connectable operably to so train said gun, a variable discharge :pump connected to drive said motor, said pump including a member translatable from a first to a second position to varythe discharge of said pump from maximum delivery in one direction to maximum delivery in the opposite direction, hydraulic power means connected with .said member to positively translate the same between said positions, a gyroscope mountable on said base tor precession in response to change in course .or heading of said base, first-and second coils energizable to control the admission of pressure fluid to said hydraulic power means to effect the translation of said member in respectively opposite directions, an element including a pair of spaced follow-up contacts. means adapted to move said element by and in response to movement of said hydraulic power means, a .pair of control circuits each including a contact and a respective coil, a trolley movable over and in alternative engagement with said contacts, means urging said trolley to a predetermined position, means operable by and in response to precession of said gyroscope operating said trolley over said contacts to close the circuit through said trolley and one of said coils, a manually operable control device for said power means, a driving connection betweensaid device and said gyroscope, and means manually movable between a first and second position to place said power means under direct control of said device or alternatively under direct control of said gyroscope.

2. In an azimuth control system adapted to be used for a gun trainable about a normally vertical axis on and with respect to a vehicle, power means connectable operably to so train said gun relatively to said vehicle, first control means for said .power means to control the rate and direction of training of said gun, a gyroscope mountable on said vehicle and adapted to precess in response to torque applied about a normally vertical axis, a single manually operable device connected to said first control means, second control means under control of said gyroscope in response to precession thereof to control said power means, and means operable at will to vshift direct control of said power means from said first to said second control means, said operable means operable to place said power means under direct and complete control of said first control means.

3. An azimuth stabilizer system adapted to be used for a gun mounted on a vehicle and trainable relatively thereto about a normally vertical axis, a hydraulic motor connectable operably to so train said gun, a variable displacement pump connected to drive said motor, first and second control means for said pump, each operable to individually control the direction and rate of discharge of said pump, manually operable means to actuate said first control means, a gyroscope mountable onsa'id vehicle and adapted to precess in response to change in azimuth of said gun, means including an electric circuit actuating said second control means in response to precession of said gyroscope, a switch in said circuit, and a control rod movable to a 'first position closing said switch and rendering said first control means completely ineffective, or to a second position opening said switch and rendering said first control means efiective, and at the same time rendering saidsecond control means completely ineffective.

4. In an azimuth stabilizing and training system .able means to a predetermined neutral position,

adapted to be :used for a gun mounted upon a mobile base ,for traversing relatively thereto about a normally vertical axis, power means connectable operably to so traverse said gun, first and second control means each operable to control the operation of said power means indirection and rate of operation, a, gyroscope mountable on said basefor precession operablyin response to movement of said base in azimuth, means adapted to be operated by said gyroscope and adapted to control second control means in accordance with the precession-of said gyroscope to eir'ect'a corresponding direction and rate of movement of said power means, manually operable meansrfior operating saidfirst control means, means manually operable to shift direct control of said power means alternatively between said first and said second control means, a driving connection between said manually operable means and said gyroscope, said connection including a spring connected to apply precessing torques to said gyroscope in opposite directions of rotation for respective directions of movement of said manually operable means, said spring adapted to return said manually operand means adjustable to balance said gyroscope abouta given center .of gravity.

5. In an azimuth stabilizerand control system adapted for use with a gun mounted on a vehicle and movable in train relatively thereto about a normally vertical axis, a reversible hydraulic motor .connectable to operably so train the gun, a reversible rotary pump for driving said motor, said pump including a slide block arranged to operably control direction and rate of delivery of said pump .and normally urged to centralized, no-discharge position, a control cam engaging said slide block and shiftable in translation to correspondingly move said slide block, .first fluid pressure means for shifting said control cam, manually controllable valve means for controlling said fluid pressure means, a pair of insulated unitary follow-up contacts, a cylinder, a piston in said cylinder connected .to shift said slide block and said follow-up contacts, fluid pressure connections to said cylinder on opposite sides of the piston therein, first and second coils each energizable to admit pressure fluid to a respective one of said connections, whereby energization of said first coil urges said slide block into engagement with said control cam, a constrained rate-responsive gyroscope adapted to be mountably carried by the vehicle and adapted to operably precess in response .to angular movement of the gun about said vertical axis, third and fourth coils, resistance means differentially energizing said third and fourth coils in response to the direction and amount of precession of said gyroscope, a follow-up contact arm movable to engage either .of said follow-up contacts and positionally controllable operably in response to diiferentialenergization of said third and fourth coils, a first switch connected vwith said control cam to be closed thereby only when the negative portion of said cam is in engagement with said slide block, a second switch having an .arm connected with a source of potential and having first and second contacts selectively engageable by the arm, manually operable control means connected to said switch arm and said first fluid pressure means, and movable from a first positionin which said switch arm engages said first switch contact and said controllable valve means is simultaneously operated to move said control cam out of contact with said slide block, to a second position in which said arm engages said second switch contact and said controllable valve means is released, a handle for operating said controllable valve means when released, a circuit including the source of potential, switch arm and first contact of said second switch, said first switch and jfirst coil, a second circuit including said resistance means, second contact of said second switch and said follow-up contact arm, and a driving connection between said'handle and gyroscope whereby said gyroscope maybe caused to precess in either direction in response to a corresponding movement of said handle.

References Cited in the file of this patent UNITED STATES PATENTS 5 1,201,105 Saqui et a1. Oct. 10, 1916 1,238,503 Fiske et al. Aug. 28, 1917 1,296,303 Manly Mar. 4, 1919 1,853,069 Minorsky Apr. 12, 1932 1,919,191 Bates July 25, 1933 0 

